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[en] The primary goal of the larger research program, of which this work is one component, is to restore the hydrodynamics and energy gradients of targeted Savannah River Site (SRS) streams to a condition comparable to local natural streams or rivers of similar order, and to stabilize sediment transport (net degradation/aggregation) with the assumption that the faunal components of these systems will quickly recover on their own (e.g., Pen Branch; Lakly and McArthur, 2000). This work is specifically focused on the identification of near-stream floodplain areas that exhibit sediment deposition or erosion, and the quantification of these processes over a historical time scale (last ~100 years).
[en] While extensive research consideration has been given to the Northern Hemispheric polar (PJ) and subtropical jet (STJ) streams, there have been fewer climatological studies relating these two jet types to tornado outbreaks. This study examines tornado outbreaks in two regions with substantial tornado risk, Plains Tornado Alley (PTA) and Southeast Tornado Alley (STA), and classifies the jet streak types associated with the outbreaks. Utilizing the Storm Prediction Center (SPC) tornado database and an objective jet identification scheme created from NCEP/NCAR Reanalysis 1 data, jet streaks were identified as STJ, PJ, merged (identified as STJ and PJ), superposed, or unidentified for a 30-year period between 1984 and 2013. Tornado outbreaks were categorized into different types based on these jet streak types. Results revealed STJ and PJ tornado outbreaks compose the majority of tornado outbreaks, as well as the most intense outbreaks, in both PTA and STA. STJ tornado outbreaks were found to be more common in PTA than in STA, while PJ outbreaks were more common in STA than in PTA. The study concludes by considering how a coupled jet structure may be important for tornado outbreaks.
[en] To examine whether stream nitrogen concentrations in forested reference catchments have changed over time and if patterns were consistent across the USA, we synthesized up to 44 yr of data collected from 22 catchments at seven USDA Forest Service Experimental Forests. Trends in stream nitrogen presented high spatial variability both among catchments at a site and among sites across the USA. We found both increasing and decreasing trends in monthly flow-weighted stream nitrate and ammonium concentrations. At a subset of the catchments, we found that the length and period of analysis influenced whether trends were positive, negative or non-significant. Trends also differed among neighboring catchments within several Experimental Forests, suggesting the importance of catchment-specific factors in determining nutrient exports. Over the longest time periods, trends were more consistent among catchments within sites, although there are fewer long-term records for analysis. These findings highlight the critical value of long-term, uninterrupted stream chemistry monitoring at a network of sites across the USA to elucidate patterns of change in nutrient concentrations at minimally disturbed forested sites. (letter)
[en] A plant theoretically capable of generating a 24/7 continuous induced air stream and the concept of this plant are described, as well as its operational principle and materials from which the plant will be manufactured. Arguments in favor of the relevance of this plant are adduced.
[en] This paper investigates monthly, seasonal, and annual trends in rainfall, streamflow, temperature, and humidity amounts at Urmia lake (UL) basin and analyzes the interaction between these variables and UL’s water level fluctuation during the 1971–2013 period. Two new methods including nonparametric hybrid wavelet Mann–Kendall test and Şen’s methodology have been used to determine potential trends in the variables and their dominant periods. The results showed significant decreasing trends in the water level and streamflow series, moderate decreasing trend in the rainfall and relative humidity series, and increasing trends in the observed temperature data. The 8- , 12-month, and 2-year periods were detected as the dominant periods of the variables in monthly, seasonal, and annual timescales, respectively. The results from the interaction analysis revealed that the main factor influencing the water level at UL is decreasing trend in the streamflow series. Both the monthly series of UL’s water level and the streamflow series of the stations indicated two start points of significant decreasing trend in 1973 and 1998. Furthermore, a comparative analysis among the applied methods indicated a good agreement between the results of hybrid wavelet Mann–Kendall test and Şen’s trend analyzing method.
[en] This paper reports dynamical characteristics of the seasonal circulations over the Korean peninsula. It consists of summary, research method, result, consideration and conclusion. It introduces the method of research ; characteristics of circulation over seasonal wind in Asia, characteristic of upper jet stream related cold wave and monsoon in East Asia and dynamics of pulsation and maintain of high atmospheric pressure in siberia in winter. It was reported by Korea science foundation in 1989.